If, either when running a perl program or when trying to update cpan, you get an error like this:
Use of uninitialized value in concatenation (.) or string at /usr/lib/perl5/5.8.8/i386-linux-thread-multi/Scalar/Util.pm line 30.
You’ve probably screwed up the Scalar Util stuff. Reinstall a new one from source.
wget http://search.cpan.org/CPAN/authors/id/G/GB/GBARR/Scalar-List-Utils-1.19.tar.gz tar xvzf Scalar-List-Utils-1.19.tar.gz cd Scalar-List-Utils-1.19 perl Makefile.PL make make test make install
That fixed things for me.